Projer

The app would be helpful for freelancers or startups.

It has a straightforward hierarchy:

There is a list of customers, where every customer has a list of projects.
Every project has a list of sessions and payments.
Sessions count the time of completed work, multiply it by hourly rate and calculate the debt of the customer,
whereas Payments reduce the debt of the customer.

The app is free and without adds.
Supports tablet PCs.

New functionality will be added gradually.